The risk haplotype of the OR12D2 gene in autism subjects and the overexpression of OR12D2 in the brain, dysfunction in neurodegenerative processes, olfactory impairment, and the overuse of aroma compounds or essential oils, flowers, aromatic wood, herbs, frankincense, and perfumes among the Arab population provide clues that olfactory sensory deficits and overexpression of OR12D2 should be studied in detail among the Arab population to reveal the underlying etiology of autism [18,19,20,21,39,40]. This evidence concerns the gene OR12D2 and autism.